1. Field of the Invention
The present invention relates generally to gaskets for air conditioners, and more specifically to a gasket, in an automotive air conditioner having a plurality of separate air conditioning units, for providing a pressure-tight seal between the units.
2. Description of the Prior Art
In FIG. 1, a typical automotive air conditioner is shown which has a plurality of air conditioning units including a fan unit 1 having a built-in fan 2, a cooling unit 3 having a built-in evaporator 4 and a heater unit 5 having a built-in heater 6. The units are joined together at the joints 7 and 8, with respective gaskets 9 fitted between mating surfaces thereof. Referring to FIG. 2, which is an enlarged sectional view of the joint 8, the gasket 9 is interposed between the sealing surfaces 10 and 11 of the units 3 and 5. The gasket 9 is bonded at one side thereof by a bonding agent 12 to the sealing surface 11 and at the other side forcedly brought into contact with the sealing surface 10, thereby providing a seal between the units 3 and 5. This kind of prior art gasket is usually made of an elastic foam material such as urethane foam so that it is elastic, readily deformable and sufficiently compressible. However, since such a gasket contains numerous pores or interstices, it is somewhat permeable. Leakage of air in an insufficiently conditioned state can therefore occur. Furthermore, water leakage can also occur. That is, when the vehicle body vibrates causing the joints 7 and 8 to vibrate, the pores 13 in the gasket 9 are alternately compressed and expanded. As a result, the gasket 9 effects a pumping action, sucking the water remaining in the air conditioner and pumping it through the gasket to leak out. Thereafter, water leakage continues by capillary action.
For the purpose of eliminating the above drawbacks, there has been proposed a gasket that has been treated with a tar or like substance so that the gasket repells moisture and avoids the pumping effect. However, such a gasket is not wholly satisfactory.